Mammalian chemical signals emitted by one individual can cause hormonal changes in a conspecific recipient resulting in alteration of several reproductive functions (e.g. acceleration of puberty, estrous cycle regulation and release from estrous suppression). chemical signals which act to alter reproductive physiology are termed primer pheremones. Hormonal response to conspecific chemosignals often act by increasing luteinizing hormone (LH). Primer-like pheromone effects in humans include an alteration of the length and timing of the menstrual cycle using serial applications of male or female axillary secretion extracts upon females. Since axillary secretions appear to be the "best candidate" human odor source with chemical communicatory properties, we are conducting research to (a) develop a reliable method to assess chemical constituents for pheromone-like activity and (b) determine the chemical character of axillary secretions. Research within the GCRC is employing the application of a male axillary extract to the nasal area of female volunteers to determine its affect upon the pulse pattern of LH. We will employ this bioassay to guide an analytical study into the active axillary extract constituents. In addition to directing us to the active components, this study will help elucidate neuroendocrine mechanism involved in olfactory modulation of the menstrual cycle.